Thank you so much for all the answers!
To sum this thread up for me: TiddlyWiki will not be my solution. I want an internet facing Wiki with strong security and a reliable permission model (I want also to set up accounts for our customers with restrictive read permissions) and I also don’t want to spend to many time to set it up.
So now let’s look at some alternatives:
I read a lot of good stuff about Notion, but I think the biggest problem I have with Notion is that there is no automatic backup function. What happens if the company behind Notion is bankrupt tomorrow and the servers are down? Can I easily change to another software with the backup? If I read correctly this is not possible.
To avoid such problems I would prefer to host a wiki on our own server. If there is a real unique and awesome wiki, which you can’t host on our own servers, than it needs at least an automatic backup service (to a source of our choice) and an easy way to migrate to another wiki software.
Currently on my shortlist:
- DokuWiki - this seems to be closest to TiddlyWiki: no database, flexible and easy to customize with lots of plugins. Free and open-source
- BlueSpice Wiki - based on MediaWiki with additional tweaks and plugins. The free version is free and open-source, the pro version costs 3100€/year with on-promises installation
- XWiki - the base version is free and open-source, with the Pro version you get additional plugins. 2000€/year with on-promises installation
What I really like about TiddlyWiki and which would be nice to have on the other wiki software is an easy way to create templates and buttons. It should also be user-friendly for non-coder.
Any thoughts?